<template>

  <div class="app-container">

    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="最终发布"/>
    </el-steps>

    <el-form label-width="120px">

  <el-form-item label="课程标题">
    <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
  </el-form-item>

  <!-- 一级分类 -->
  <el-form-item label="课程类别">
    <!-- change事件：域对象改变事件，域对象的数据发生改变就会触发  -->
    <el-select
      @change="subjectLevelOneChanged"
      v-model="courseInfo.subjectParentId"
      placeholder="请选择">
      <el-option
        v-for="subject in subjectOneList"
        :key="subject.id"
        :label="subject.title"
        :value="subject.id"/>
    </el-select>
    <!-- 二级分类 -->
    <el-select 
      v-model="courseInfo.subjectId"
      placeholder="请选择">
      <el-option
        v-for="subject in subjectTwoList"
        :key="subject.value"
        :label="subject.title"
        :value="subject.id"/>
    </el-select>
  </el-form-item>

  <!-- 课程讲师 TODO -->
  <!-- 课程讲师 -->
    <el-form-item label="课程讲师">
      <el-select
          v-model="courseInfo.teacherId"
          placeholder="请选择">
          <el-option
          v-for="teacher in teacherList"
          :key="teacher.id"
          :label="teacher.name"
          :value="teacher.id"/>
      </el-select>
    </el-form-item>

  <el-form-item label="总课时">
    <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
  </el-form-item>

  <!-- 课程简介 TODO -->
  <!-- 课程简介-->
  <el-form-item label="课程简介">
      <tinymce :height="300" v-model="courseInfo.description"/>
  </el-form-item>

  <!-- 课程封面 TODO -->
  <!-- 课程封面-->
  <el-form-item label="课程封面">
    <el-upload
      :show-file-list="false"
      :on-success="handleAvatarSuccess"
      :before-upload="beforeAvatarUpload"
      :action="BASE_API+'/eduoss/file/upload?host=cover'"
      class="avatar-uploader">
      <img :src="courseInfo.cover" width="300" height="300">
    </el-upload>
  </el-form-item>

  <el-form-item label="课程价格">
    <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
  </el-form-item>

  <el-form-item>
    <el-button :disabled="saveBtnDisabled" type="primary" @click="next">保存并下一步</el-button>
  </el-form-item>
</el-form>


  </div>
</template>
<script>
import course from '@/api/edu/course'
import teacher from '@/api/edu/teacher'
import subject from '@/api/edu/subject'

import Tinymce from '@/components/Tinymce'

const defaultForm = {
  title: '',
  subjectId: '',
  teacherId: '',
  lessonNum: 0,
  description: '',
  cover: process.env.OSS_PATH + '/cover/default_cover.jpg',
  price: 0
}

export default {
  components: { Tinymce }, // 声明Tinymce（富文本）组件
  data() {
    return {
        BASE_API: process.env.BASE_API,
        courseInfo: defaultForm,
        saveBtnDisabled: false, // 保存按钮是否禁用
        teacherList: [], // 讲师列表
        subjectOneList: [], // 一级分类列表
        subjectTwoList: [] // 二级分类列表
    }
  },
  watch: {
    $route(to, from) {
      console.log('watch $route')
      this.init()
    }
  },

  created() {
    this.init()
  },

  methods: {
    init() {
      if (this.$route.params && this.$route.params.id) {
          const id = this.$route.params.id
          // 根据id获取课程基本信息(课程信息回显)
          this.fetchCourseInfoById(id)
      } else {
          this.courseInfo = { ...defaultForm }
          // 获取讲师列表
          this.initTeacherList()
          // 初始化课程分类列表
          this.initSubjectList()
      }    
    },

    initTeacherList() {
        teacher.getList()
          .then(response => {
            this.teacherList = response.data.items
          })
    },

    initSubjectList() {
      subject.getSubjectList()
        .then(response => {
          this.subjectOneList = response.data.items
        })
    },

    // 点击一级分类对象，显示对应的二级分类数据
    subjectLevelOneChanged(value) {
      // value：一级分类的id值
      for (let i = 0; i < this.subjectOneList.length; i++) {
        if (this.subjectOneList[i].id === value) {
            this.subjectTwoList = this.subjectOneList[i].children
            // 把原二级分类id值清空
            this.courseInfo.subjectId = ''
        }
      }
    },

    // 课程信息回显
    fetchCourseInfoById(id){
      course.getCourseInfoById(id)
        .then(responseCourse => {
          this.courseInfo = responseCourse.data.item
          // 初始化课程分类列表
          subject.getSubjectList()
            .then(responseSubject => {
              this.subjectOneList = responseSubject.data.items
              for (let i = 0; i < this.subjectOneList.length; i++) {
                if (this.subjectOneList[i].id === this.courseInfo.subjectParentId) {
                    this.subjectTwoList = this.subjectOneList[i].children
                }
              }
            })
          
          // 获取讲师列表
          this.initTeacherList()
        })
        .catch(response => {
          this.$message({
            type: 'error',
            message: response.message
          })
        })
    },

    next() {
      this.saveBtnDisabled = true
      if (!this.courseInfo.id) {
        this.saveData()
      } else {
        this.updateData()
      }
    },
    // 保存下一步
    saveData(){
        course.saveCourseInfo(this.courseInfo)
          .then(response => {
            this.$message({
                type: 'success',
                message: '保存成功!'
            })
          return response// 将响应结果传递给then
          })
          .then(response => {
            this.$router.push({ path: '/edu/course/chapter/' + response.data.courseId })
          })
          .catch((response) => {
            this.$message({
                type: 'error',
                message: response.message
            })
          })
        
    },
    // 更新课程
    updateData(){
        this.saveBtnDisabled = true // 防止用户多次点击
        course.updateCourseInfoById(this.courseInfo)
          .then(response => {
            this.$message({
                type: 'success',
                message: '修改成功!'
            })
            console.log(response.data.courseId)
            return response// 将响应结果传递给then
          }).then(response => {
              this.$router.push({ path: '/edu/course/chapter/' + response.data.courseId })
          }).catch(() => {
            this.$message({
                type: 'error',
                message: "修改失败！"
            })
          })
        
    },

    // 封面传成功响应
    handleAvatarSuccess(res, file) {
      console.log(res)// 上传响应
      console.log(URL.createObjectURL(file.raw))// base64编码
      this.courseInfo.cover = res.data.url
    },
    // 封面上传之前做判断
    beforeAvatarUpload(file) {
      const isJPG = file.type === 'image/jpeg'
      const isLt2M = file.size / 1024 / 1024 < 2

      if (!isJPG) {
        this.$message.error('上传头像图片只能是 JPG 格式!')
      }
      if (!isLt2M) {
        this.$message.error('上传头像图片大小不能超过 2MB!')
      }
      return isJPG && isLt2M
    }

  }
}
</script>
<style scoped>
/* Tinymce调整上传图片按钮的高度 */
.tinymce-container {
  line-height: 29px;
}
</style>